Method of carburizing.



lJNlTED STATES PATET FFlI CF.

IETJ'GE RODMAN, F EDGEWOOD, PENNSYLVANIA, ASSIGNOR T0 R-OZDMAN CHEMICAL GGMPANY, OF VEEONA, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA.

METHOD OF CARBURIZING.

0 Drawing.

of which the the following is a specification. I

This invention relates to the carburizing of steel and discloses a new and improved method of maintaining the efficiency of the carburizinp material,

oient carbon has been ahsorbed by soda ash, the idea Steel is packed with carburizing material in pots or boxes and then subjected to 1500 to 1800 degrees Fahrenheit. When suffithe steel ;he not is withdrawn from the furnace and then either cooled down or opened up while still hot. in the latter case the carburizing material is liable to burn and lose its carburizing efficiency andtherefore it is customary either to cool the material in an air tight receptacle (sometimes the box or pot after the metal parts have been removed) or to quench it with water, generally by sprinkling and raking the material about on the door till cool enough to resist ignition.

'Whether the material is cooled in the boxes without opening them or is exposed hot and afterward cooled in any desired way, the user frequently adds some additional energizer (generally soda ash in the fhrm of a fine powder) to bring the material up to a standard strength. This is done by mixing the used. material with a little dry being to compensate for the alkali which may have been vaporized during the carburizing heat or which may have been burned out during the exposure of the material hot to the air.

ll find that a more satisfactory way of adding the alkali and of cooling the material when it is taken hot from the boxes is to make a solution of soda ash, or a solution of soda ash and common salt if preferred, and sprinkle the hot material with the solution rather than with the water only. In this way the energizer is carried by'the solution into the pores of the carburizing material and so remains in fairly uniform distribution throughout the mass of material;

whereas, when the powdered energizer is added to the dry material there is no impregnation and practically no adhesion and the energizer frequently separates from the granular carbonaceous material and settles burization.

Specification of Letters Fatent. Patented Jan, 28, 1919,

Application filed June 16, 1917. Serial No. 175,235.

as a layer at the bottom of the pile of material, or at the bottom of the pot after packing, thereby making for un-uniform car- This defect is overcome by my invention and the coolingof'the material and the uniform addition of the energizer is accomplished at one step; I have used this scheme on a large scale, where thousands of uniform parts of low carbon iron have been carbonized and afterward tested and I am convinced that this method of cooling the carburizing material not-only of considerable value as a means of maintaining the material at full strength, but it also is valuable as a means of keeping the material and the work produced uniform. The strength of the solution will vary with the temperature and time in the furnace, and with the degree to which the material is cooled, but I find a satisfactory strength, where soda ash alone is used, to be about ten parts of dry soda ash (sodium carbonate) to one hundred parts of water. \Vhere common salt is also used I prefer to mix seven parts of salt and seven parts of soda ash with one hundred parts of water. This can conveniently be handled in an ordinary sprinkl-ingfcan; but more elaborate sprinkling devices may be utilized if desired.

The material which I have cooled on a large scale with such a solution of soda ash consisted of small masses (about one-quarter inch in through dimension) made by mixing finely ground coking coal with powdered energizers, coking this mixture and then crushing the resultant coke to produce the and small masses above. The solution method are, however, applicableto other types of carburizing materials. The material is cooled by sprinkling and stirring, with a hoe or shovel, until below a red heat but the sprinkling is not continued so as to leave the material wet. I have found that material which was more or less unsatisfactory when handled in ordinary wayscould be maintained highly e'flicient by the method outlined and the uniformity of the metal parts carburized greatly increased. i

What I claim is: V

1. The method of maintaining the strength and rniformity of carburizing material which consists in sprinkling the used material, while still hot, with a' solution of an energizing material, 1

'2. The method of maintaining the strength which consists in subjectingt e and uniformity of carburizing material which consists in sprinkling the used material, While still hot, with a solution of soda ash,

3. The method of maintaining the strength and uniformity. of carburizin materials, used and hot material to the cooling action of a solution of energizing material.

4. The method of uniformly impregnatiug used carburizing materials, which consists in cooling the used and hot material with a solutionof energizing material.

5, The method of maintainingthe strength and uniformity of carburizing material which consists in subjecting the used and hot material to the cooling action of a solution of soda ash and salt.

6. The method of maintaining the strength and uniformity of carburizing material, which consists in subjecting hot, used carburizing material to the action of energizing material.

7. The method of uniformly impregnating used carburizing materials, which consists in subjecting hot, used material to a solution of impregnating material for the purpose of cooling the carburizing material and impregnating it With the material in solution. v

In testimony whereof, I have hereunto subgcribed my name this 13 day of June, 191

HUGH RODMAN. Witnesses:

R. L. KENT, ANNA CLOHERTY. 

